… In Keystone, Tom Steyer, a fifty-six-year-old billionaire, former hedge-fund manager, and major donor to the Democratic Party, has picked an issue that enables him to win regardless of Obama’s decision. Leading the fight against the pipeline will help him in a future political campaign in his home state. “He’s now won two major ballot campaigns in California, and has an incredibly strong relationship with both labor and environmentalists, in a state where it costs fifty million dollars to be a competitive candidate,” Lehane said. “In terms of California brand and California politics, he’s in a pretty sweet place.”

The stakes for Obama are higher. There are few opportunities to influence the politics of climate change and leave a legacy on the issue. If he intends to lead an effort to write an international treaty on climate change, as he has promised, taking a stand against the oil sands would provide moral authority in those negotiations, Steyer said: “If you want a leadership position, you have to make public, hard decisions, stick with them, and lead. Everyone’s watching this around the world. Everyone knows this is his big choice. You can’t whiff on the big choices and then turn around and say, ‘But, you know, we really are leading on this—except when it’s inconvenient to us.’ ”

Whether or not the pipeline was the correct battle to wage over climate change, it is now Obama’s. “Sometimes you don’t get to pick the perfect fight,” Steyer said. “Sometimes, someone punches you in the face and you’re in the fight.”